[PATCH 3/3] dmaengine: Fix client_count is countered one more incorrectly.

[PATCH 3/3] dmaengine: Fix client_count is countered one more incorrectly.

[Koba Ko]

If the passed client_count is 0,
it would be incremented by balance_ref_count first
then increment one more.
This would cause client_count to 2.

cat /sys/class/dma/dma0chan*/in_use
2
2
2

Fixes: d2f4f99db3e9 ("dmaengine: Rework dma_chan_get")
Signed-off-by: Koba Ko <koba.ko@canonical.com>
---
 drivers/dma/dmaengine.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index 2cfa8458b51be..78f8a9f3ad825 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -451,7 +451,8 @@ static int dma_chan_get(struct dma_chan *chan)
 	/* The channel is already in use, update client count */
 	if (chan->client_count) {
 		__module_get(owner);
-		goto out;
+		chan->client_count++;
+		return 0;
 	}
 
 	if (!try_module_get(owner))
@@ -470,11 +471,11 @@ static int dma_chan_get(struct dma_chan *chan)
 			goto err_out;
 	}
 
+	chan->client_count++;
+
 	if (!dma_has_cap(DMA_PRIVATE, chan->device->cap_mask))
 		balance_ref_count(chan);
 
-out:
-	chan->client_count++;
 	return 0;
 
 err_out:
-- 
2.25.1

Re: [PATCH 3/3] dmaengine: Fix client_count is countered one more incorrectly.

[Jie Hai]

Hi, Koba Ko

Thanks for your patch.

I've had the same problem,see
https://lore.kernel.org/all/20220716024453.1418259-1-haijie1@huawei.com/.

The two operations of updating client_count, that is,
     chan->client_count++;
     balance_ref_count(chan);

the order of which is modified by d2f4f99db3e9 ("dmaengine: Rework 
dma_chan_get").

I have complied and tested it on my arm64 and this patch does
fix the problem.

For this patch,
Reviewed-by: Jie Hai <haijie1@huawei.com>
Test-by: Jie Hai <haijie1@huawei.com>

Best regards,
Jie Hai

On 2022/8/30 17:32, Koba Ko wrote:
> If the passed client_count is 0,
> it would be incremented by balance_ref_count first
> then increment one more.
> This would cause client_count to 2.
> 
> cat /sys/class/dma/dma0chan*/in_use
> 2
> 2
> 2
> 
> Fixes: d2f4f99db3e9 ("dmaengine: Rework dma_chan_get")
> Signed-off-by: Koba Ko <koba.ko@canonical.com>
> ---
>   drivers/dma/dmaengine.c | 7 ++++---
>   1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
> index 2cfa8458b51be..78f8a9f3ad825 100644
> --- a/drivers/dma/dmaengine.c
> +++ b/drivers/dma/dmaengine.c
> @@ -451,7 +451,8 @@ static int dma_chan_get(struct dma_chan *chan)
>   	/* The channel is already in use, update client count */
>   	if (chan->client_count) {
>   		__module_get(owner);
> -		goto out;
> +		chan->client_count++;
> +		return 0;
>   	}
>   
>   	if (!try_module_get(owner))
> @@ -470,11 +471,11 @@ static int dma_chan_get(struct dma_chan *chan)
>   			goto err_out;
>   	}
>   
> +	chan->client_count++;
> +
>   	if (!dma_has_cap(DMA_PRIVATE, chan->device->cap_mask))
>   		balance_ref_count(chan);
>   
> -out:
> -	chan->client_count++;
>   	return 0;
>   
>   err_out:

Re: [PATCH 3/3] dmaengine: Fix client_count is countered one more incorrectly.

[Jerry Snitselaar]

On Tue, Aug 30, 2022 at 05:32:07PM +0800, Koba Ko wrote:
> If the passed client_count is 0,
> it would be incremented by balance_ref_count first
> then increment one more.
> This would cause client_count to 2.
> 
> cat /sys/class/dma/dma0chan*/in_use
> 2
> 2
> 2
> 
> Fixes: d2f4f99db3e9 ("dmaengine: Rework dma_chan_get")
> Signed-off-by: Koba Ko <koba.ko@canonical.com>

Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com

> ---
>  drivers/dma/dmaengine.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
> index 2cfa8458b51be..78f8a9f3ad825 100644
> --- a/drivers/dma/dmaengine.c
> +++ b/drivers/dma/dmaengine.c
> @@ -451,7 +451,8 @@ static int dma_chan_get(struct dma_chan *chan)
>  	/* The channel is already in use, update client count */
>  	if (chan->client_count) {
>  		__module_get(owner);
> -		goto out;
> +		chan->client_count++;
> +		return 0;
>  	}
>  
>  	if (!try_module_get(owner))
> @@ -470,11 +471,11 @@ static int dma_chan_get(struct dma_chan *chan)
>  			goto err_out;
>  	}
>  
> +	chan->client_count++;
> +
>  	if (!dma_has_cap(DMA_PRIVATE, chan->device->cap_mask))
>  		balance_ref_count(chan);
>  
> -out:
> -	chan->client_count++;
>  	return 0;
>  
>  err_out:
> -- 
> 2.25.1
> 

Re: [PATCH 3/3] dmaengine: Fix client_count is countered one more incorrectly.

[Dave Jiang]

On 8/30/2022 2:32 AM, Koba Ko wrote:
> If the passed client_count is 0,
> it would be incremented by balance_ref_count first
> then increment one more.
> This would cause client_count to 2.
>
> cat /sys/class/dma/dma0chan*/in_use
> 2
> 2
> 2
>
> Fixes: d2f4f99db3e9 ("dmaengine: Rework dma_chan_get")
> Signed-off-by: Koba Ko <koba.ko@canonical.com>

Reviewed-by: Dave Jiang <dave.jiang@intel.com>


> ---
>   drivers/dma/dmaengine.c | 7 ++++---
>   1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
> index 2cfa8458b51be..78f8a9f3ad825 100644
> --- a/drivers/dma/dmaengine.c
> +++ b/drivers/dma/dmaengine.c
> @@ -451,7 +451,8 @@ static int dma_chan_get(struct dma_chan *chan)
>   	/* The channel is already in use, update client count */
>   	if (chan->client_count) {
>   		__module_get(owner);
> -		goto out;
> +		chan->client_count++;
> +		return 0;
>   	}
>   
>   	if (!try_module_get(owner))
> @@ -470,11 +471,11 @@ static int dma_chan_get(struct dma_chan *chan)
>   			goto err_out;
>   	}
>   
> +	chan->client_count++;
> +
>   	if (!dma_has_cap(DMA_PRIVATE, chan->device->cap_mask))
>   		balance_ref_count(chan);
>   
> -out:
> -	chan->client_count++;
>   	return 0;
>   
>   err_out:

Re: [PATCH 3/3] dmaengine: Fix client_count is countered one more incorrectly.

[Jerry Snitselaar]

On Tue, Aug 30, 2022 at 05:32:07PM +0800, Koba Ko wrote:
> If the passed client_count is 0,
> it would be incremented by balance_ref_count first
> then increment one more.
> This would cause client_count to 2.
> 
> cat /sys/class/dma/dma0chan*/in_use
> 2
> 2
> 2
> 
> Fixes: d2f4f99db3e9 ("dmaengine: Rework dma_chan_get")
> Signed-off-by: Koba Ko <koba.ko@canonical.com>
> ---
>  drivers/dma/dmaengine.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
> index 2cfa8458b51be..78f8a9f3ad825 100644
> --- a/drivers/dma/dmaengine.c
> +++ b/drivers/dma/dmaengine.c
> @@ -451,7 +451,8 @@ static int dma_chan_get(struct dma_chan *chan)
>  	/* The channel is already in use, update client count */
>  	if (chan->client_count) {
>  		__module_get(owner);
> -		goto out;
> +		chan->client_count++;
> +		return 0;
>  	}
>  
>  	if (!try_module_get(owner))
> @@ -470,11 +471,11 @@ static int dma_chan_get(struct dma_chan *chan)
>  			goto err_out;
>  	}
>  
> +	chan->client_count++;
> +
>  	if (!dma_has_cap(DMA_PRIVATE, chan->device->cap_mask))
>  		balance_ref_count(chan);
>  
> -out:
> -	chan->client_count++;
>  	return 0;
>  
>  err_out:
> -- 
> 2.25.1
> 

Hi Vinod,

Any thoughts on this patch? We recently came across this issue as well.

Thanks,
Jerry

Re: [PATCH 3/3] dmaengine: Fix client_count is countered one more incorrectly.

[Vinod Koul]

On 29-09-22, 09:57, Jerry Snitselaar wrote:
> On Tue, Aug 30, 2022 at 05:32:07PM +0800, Koba Ko wrote:

> 
> Hi Vinod,
> 
> Any thoughts on this patch? We recently came across this issue as well.

I have only patch 3, where is the rest of the series... ?

-- 
~Vinod

Re: [PATCH 3/3] dmaengine: Fix client_count is countered one more incorrectly.

[Jerry Snitselaar]

On Thu, 2022-09-29 at 22:40 +0530, Vinod Koul wrote:
> On 29-09-22, 09:57, Jerry Snitselaar wrote:
> > On Tue, Aug 30, 2022 at 05:32:07PM +0800, Koba Ko wrote:
> 
> > 
> > Hi Vinod,
> > 
> > Any thoughts on this patch? We recently came across this issue as
> > well.
> 
> I have only patch 3, where is the rest of the series... ?
> 

I never found anything else when I looked at this earlier.
The one thing I can think of is perhaps Koba was seeing multiple
issues at time when he found this, like:

https://lore.kernel.org/linux-crypto/20220901144712.1192698-1-koba.ko@canonical.com/

That was also being seen by an engineer here that was looking
at client_count code.

Koba, was this meant to be part of a series, or by itself?


Regards,
Jerry

Re: [PATCH 3/3] dmaengine: Fix client_count is countered one more incorrectly.

[Koba Ko]

On Fri, Sep 30, 2022 at 1:26 AM Jerry Snitselaar <jsnitsel@redhat.com> wrote:
>
> On Thu, 2022-09-29 at 22:40 +0530, Vinod Koul wrote:
> > On 29-09-22, 09:57, Jerry Snitselaar wrote:
> > > On Tue, Aug 30, 2022 at 05:32:07PM +0800, Koba Ko wrote:
> >
> > >
> > > Hi Vinod,
> > >
> > > Any thoughts on this patch? We recently came across this issue as
> > > well.
> >
> > I have only patch 3, where is the rest of the series... ?
> >
>
> I never found anything else when I looked at this earlier.
> The one thing I can think of is perhaps Koba was seeing multiple
> issues at time when he found this, like:
>
> https://lore.kernel.org/linux-crypto/20220901144712.1192698-1-koba.ko@canonical.com/
>
> That was also being seen by an engineer here that was looking
> at client_count code.
>
> Koba, was this meant to be part of a series, or by itself?
>

Jerry, you're right, it's a part of the series.

>
> Regards,
> Jerry
>

Re: [PATCH 3/3] dmaengine: Fix client_count is countered one more incorrectly.

[Jerry Snitselaar]

On Fri, Sep 30, 2022 at 12:44:22PM +0800, Koba Ko wrote:
> On Fri, Sep 30, 2022 at 1:26 AM Jerry Snitselaar <jsnitsel@redhat.com> wrote:
> >
> > On Thu, 2022-09-29 at 22:40 +0530, Vinod Koul wrote:
> > > On 29-09-22, 09:57, Jerry Snitselaar wrote:
> > > > On Tue, Aug 30, 2022 at 05:32:07PM +0800, Koba Ko wrote:
> > >
> > > >
> > > > Hi Vinod,
> > > >
> > > > Any thoughts on this patch? We recently came across this issue as
> > > > well.
> > >
> > > I have only patch 3, where is the rest of the series... ?
> > >
> >
> > I never found anything else when I looked at this earlier.
> > The one thing I can think of is perhaps Koba was seeing multiple
> > issues at time when he found this, like:
> >
> > https://lore.kernel.org/linux-crypto/20220901144712.1192698-1-koba.ko@canonical.com/
> >
> > That was also being seen by an engineer here that was looking
> > at client_count code.
> >
> > Koba, was this meant to be part of a series, or by itself?
> >
> 
> Jerry, you're right, it's a part of the series.

Hi Koba,

If it is meant to be part of a series, where are patches 1 and 2?
The ccp patch has already been applied by the crypto maintainers if that
was meant to be part of a series with this patch.

Regards,
Jerry

> 
> >
> > Regards,
> > Jerry
> >

Re: [PATCH 3/3] dmaengine: Fix client_count is countered one more incorrectly.

[Koba Ko]

On Fri, Sep 30, 2022 at 1:56 PM Jerry Snitselaar <jsnitsel@redhat.com> wrote:
>
> On Fri, Sep 30, 2022 at 12:44:22PM +0800, Koba Ko wrote:
> > On Fri, Sep 30, 2022 at 1:26 AM Jerry Snitselaar <jsnitsel@redhat.com> wrote:
> > >
> > > On Thu, 2022-09-29 at 22:40 +0530, Vinod Koul wrote:
> > > > On 29-09-22, 09:57, Jerry Snitselaar wrote:
> > > > > On Tue, Aug 30, 2022 at 05:32:07PM +0800, Koba Ko wrote:
> > > >
> > > > >
> > > > > Hi Vinod,
> > > > >
> > > > > Any thoughts on this patch? We recently came across this issue as
> > > > > well.
> > > >
> > > > I have only patch 3, where is the rest of the series... ?
> > > >
> > >
> > > I never found anything else when I looked at this earlier.
> > > The one thing I can think of is perhaps Koba was seeing multiple
> > > issues at time when he found this, like:
> > >
> > > https://lore.kernel.org/linux-crypto/20220901144712.1192698-1-koba.ko@canonical.com/
> > >
> > > That was also being seen by an engineer here that was looking
> > > at client_count code.
> > >
> > > Koba, was this meant to be part of a series, or by itself?
> > >
> >
> > Jerry, you're right, it's a part of the series.
>
> Hi Koba,
>
> If it is meant to be part of a series, where are patches 1 and 2?
> The ccp patch has already been applied by the crypto maintainers if that
> was meant to be part of a series with this patch.
>
> Regards,
> Jerry

Sorry, I misunderstood. actually, there's a mistake on the [3/3] part.
I created patches for the mainline kernel before sending them to the upstream.
Then I found the first has existed on the patchwork, so removed the
[2/3] part for ccp patch and forgot to modify for this.
Should I fix this and re-submit v2(also add those review-by)?

>
> >
> > >
> > > Regards,
> > > Jerry
> > >
>

Re: [PATCH 3/3] dmaengine: Fix client_count is countered one more incorrectly.

[Vinod Koul]

On 30-09-22, 14:25, Koba Ko wrote:
> On Fri, Sep 30, 2022 at 1:56 PM Jerry Snitselaar <jsnitsel@redhat.com> wrote:

> 
> Sorry, I misunderstood. actually, there's a mistake on the [3/3] part.
> I created patches for the mainline kernel before sending them to the upstream.
> Then I found the first has existed on the patchwork, so removed the
> [2/3] part for ccp patch and forgot to modify for this.
> Should I fix this and re-submit v2(also add those review-by)?

Yes please

-- 
~Vinod